ABSTRACT The goal of the proposed project is to determine if estimates of cognitive impairment and Alzheimer?s disease and related dementias (ADRD) are biased among older adults with hearing or vision impairment. The impact of this this potential bias could be significant, as over 55% of Americans 60 years and older have either hearing or vision impairment. The specific aims of this research are to: (1) Identify and adjust for potential bias in estimates of cognitive function due to hearing or vision impairment, and (2) Quantify the across-study variation in methods used to collect and analyze cognitive data in older adults with hearing or vision loss. For aim 1, data from the Baltimore Longitudinal Study on Aging (BLSA) and the Atherosclerosis Risk in Communities Study (ARIC) will be used, as both studies used standard measures of hearing, vision, and cognition. Analyses will use cross-sectional data and an item response theory (IRT) modeling approach to: (1) disentangle the true effect of sensory impairment on cognitive function from the potential bias that sensory impairment may have on cognitive test performance; and (2) if present, correct for this potential bias and re-estimate cognitive impairment and ADRD prevalence. This aim will test the hypothesis that, after accounting for the level of cognitive ability (indexed using historical, longitudinal cognitive test data assessed in the BLSA and ARIC in years prior to the development of sensory impairment), older adults with hearing impairment systematically perform worse on cognitive tests that rely on hearing stimuli, and that older adults with vision impairment systematically perform worse on cognitive tests that rely or vision stimuli, compared to participants without these impairments. Aim 2 includes three steps: (1) Systematically identifying longitudinal cohort studies of older adults that collect cognitive testing data; (2) Administering a survey collecting information on study protocols and perform protocol abstraction to assess how cognitive function is measured and analyzed in older adults with sensory loss; and (3) Comparing the data abstracted from these protocols to assess the variation across studies in: (a) the assessment of hearing or vision, (b) exclusions from cognitive testing and analyses based on sensory impairment, (c) accommodations for sensory loss made during cognitive testing, and (d) adjustment for sensory loss in the analysis of cognitive data. We hypothesize that fewer than 50% of cohort studies surveyed use protocols for collecting and analyzing cognitive data in older adults with hearing or vision loss. The overall results of this project have crosscutting impact, as correct estimates of the prevalence and incidence of ADRD are paramount for public health planning, and etiologic research aimed at identifying approaches to reduce ADRD risk. This work will support: (1) a U13 to develop standard protocols/tools for collecting and analyzing cognitive data in older adults with sensory impairment, and (2) an R01 to implement methodological approaches to ?adjust? estimates of cognitive function for sensory impairment using longitudinal data, and a large scale effort to re-calculate these estimates.